1,3-Diiodohydantoin compound (hereinafter, also simply referred to as “DIH compound”) has been widely used as a sensitive material for photography or the like, or an iodizing agent or an oxidizing agent in production processes for medical drugs, agricultural chemicals, chemicals, or the like.
As a method for producing the DIH compounds, for example, a technique, in which a hydantoin compound is reacted with iodine monochloride in the presence of a base in an aqueous solution, has been disclosed (see, for example, JP-A-2002-30072 and J. Org. Chem., 30 (1965), 1101-1104). Such technique has advantageous points that it is simple and highly efficient as well as easy post-treatments such as purification and waste liquid treatment.
Here, in the specification of JP-A-2002-30072, a technique for purifying a DIH compound from reaction system has been described as “deposited crystal is collected by filtration, and the resultant crystal is dried under a reduced pressure”.
Meanwhile, the DIH compounds produced by the techniques or the like described in the above literatures are usually stored until the time to be used for the above applications. As such a storage method, for example, a technique, in which the compound is stored under a reduced pressure and nitrogen atmosphere in a dark place, has been disclosed (see, for example, J. Labelled Compd. Radiopharm., 44-12 (2001), 815-830).